Apparatus for heat sealing

ABSTRACT

Apparatus is provided for sealing heat sealable material with a single actuation drive train. The drive train comprises a series of gripping, heating and squeezing elements directly actuatable and sequentially staged in conjunction with eccentric linkages and the rotational position of a single drive shaft operable by a single handle and/or input source. In a manual mode the second hand of the operator is thus free to collect and position the material to be sealed, saving time and reducing operator error. The gripping and squeezing elements and their operation are also selectively programmable by the construction and orientation of the particular eccentric linkage to facilitate wide variations in the scope of sealing applications.

BACKGROUND OF THE INVENTION

The present invention refers to sealing apparatus and, moreparticularly, to the heat sealing of thermoplastic tubular members suchas collapsible dispensing tubes.

Conventional dispensing tubes in toothpaste and the like are commonlymade of plastic materials. The preparations are usually injected intothe tubes through an unseated end opposite that of the dispensing regionwhich is often tapered to a narrow diameter and capped. After the tubehas been filled, the end through which the filling took place must beclosed and sealed to prevent the contents from leaking out. This isparticularly a problem with more viscous pastes in that the considerablepressure applied to the tube to extrude it through the capped end alsobears against the sealed end. Although the formation of solid joints isno longer a technical problem with the advent of improved thermoplasticresins and polyethylene synthetic resins, the manner and efficiency inwhich such joints are formed is an ever present consideration. Forexample, certain materials such as polyethylene cannot be sealed by thedirect application of hot sealing elements or sticking is the result.Therefore, prior art technology has produced radiant heater-squeezingassemblies which effectively form leak-tight seals across tubularorifices and related open material plies.

The methods and apparatus for forming seals in thermoplastic materialshave been well defined by prior art patents. For example, U.S. Pat. No.2,691,474 to Olson discloses a thermoplastic sealing structure. TheOlson apparatus teaches the uniting of polyethylene plies with radiantheat and subsequent squeezing until the material sets. A manuallyoperable machine is likewise disclosed incorporating means for clampingthe material to be sealed in one step, providing means for heating theheating element and subsequently lowering it to close proximity with theplastic to be sealed. The operator then rotates separate handles afterreleasing the heating element to press the molten plastic into a seal.Other such prior art methods and apparatus known to the inventor hereofare as follows:

    ______________________________________                                        U.S. PAT. NO.                                                                            DATE ISSUED   INVENTOR                                             ______________________________________                                        2,928,216  3/15/60       R. Orsini                                            2,524,584  10/03/50      W. J. Zehr                                           2,987,858  6/13/61       W. C. Kerker                                         3,333,391  8/01/67       J. M. Horeth et al                                   4,019,305  4/26/77       Russell P. McGhie et al                              ______________________________________                                    

As the above references reflect, the formation of a leak-tight seals inplastic tube containers is of utmost importance for obvious sanitary andcommercial reasons. Likewise, performance consistency is critical and itis made no more apparent than in the smaller "manual" tube sealingoperations. The forming of a "good" joint in heat sealable plasticdepends upon such factors as heat intensity, heat duration, and theequally important collateral aspects of alignment, positioning and the"squeeze" time of the heated molten plastic. Such parameters are noteasy to maintain with most conventional apparatus, particularly wherethe operator must actuate a plurality of handles and/or tie up bothhands in performing the required operations.

It is a purpose of the present invention to overcome the disadvantage ofthe prior art methods and apparatus by providing a system utilizing asingle drive train for "programmed" control of the sealing stages evenwith manual actuation. The methods and apparatus as disclosed hereinprovide a radiant heating element which is constantly on at apreselected temperature and engagable with the material to be sealedonly through a sequentially staged progression necessitating only onehand of the operator. In this manner, the operator has one hand free tohandle product and concentrate on performance accuracy with few of theassociated problems of earlier methods of multi-operational stageprocedures. In addition, the incorporation of semi-automated operationis made feasible with a system depending substantially on singlerotational speed consistency as its main quality control consideration.

SUMMARY OF THE INVENTION

The invention relates to the sealing of heat sealable material, and moreparticularly, to apparatus for manually sealing heat sealable materialin a manner requiring the use of only one of the two hands of anoperator by incorporating a single actuation drive train to sequentiallygrip, heat and squeeze heat sealable material positioned therein. Theapparatus comprises a drive shaft connected to an actuation handlerotationally responsive to arcuate motion. A heat sealing element iscoupled to the drive shaft for movement in response to rotation of thedrive shaft and the heating of material disposed upon an associatedsupport frame. First and second gripping jaws are pivotally mounted tothe support frame through a first cam linkage secured upon the driveshaft adjacent the gripping jaws for cammed actuation, separation andengagement of the gripping jaws in response to rotation of the driveshaft. The gripping jaws are biased against the first cam linkage by aspring or the like. First and second squeezing jaws are disposed betweenthe gripping jaws and the heat sealing element and pivotally mounted tothe support frame through a second cam linkage secured upon the driveshaft adjacent the squeezing jaws for cammed actuation, separation andengagement of the squeezing jaws also in response to rotation of saiddrive shaft. The squeezing jaws are biased against the second camlinkage. The first and second cam linkages are connected to the driveshaft relative to the heat sealing element for sequential actuation ofthe gripping jaws and the squeezing jaws relative to the rotation of thedrive shaft by the handle and the positioning of the heating elementrelative to the material to be sealed. The operator thus needs but onehand to operate the assembly and has to make few operational decisionsas compared to conventional apparatus.

In another aspect the invention includes a method for manually sealingheat sealable material by gripping, heating and sealing said material ina single actuation bi-directional drive train and in a manner requiringthe use of only one hand of an operator. The method comprises providinga manually operable drive shaft rotatably mounted within a support frameand a heat sealing element for sealing said material. The heat sealingelement is directly coupled to the drive shaft for rotation therewith.Means are provided for gripping the material relative to a firstrotatable position of said drive shaft and for squeezing the materialrelative to a third rotatable position of said drive shaft. The materialis then disposed adjacent the drive train with the drive shaft in aninitial open, rotatable position. The drive shaft is rotated in a firstdirection to a first position of arcuate displacement to grip thematerial relative to the drive shaft. Next, the drive shaft is rotatedto a second position of greater arcuate displacement and wherein theheat sealing element is adjacent the material. The drive shaft is thenrotated in a second, opposite direction to a third position between thefirst and second positions wherein the heat sealing element is displacedfrom the material and the heated material squeezed to form a seal. Whenthe drive shaft is rotated back in to its initial rotational positionthe sealed material may be removed and new material inserted. Suchmethods and apparatus are particularly applicable to open ended,thermoplastic dispensing tubes.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and forfurther objects and advantages thereof, reference may be now had to thefollowing description taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a perspective view of one embodiment of the apparatusconstructed in accordance with the principles of the present invention.

FIG. 2 is an enlarged fragmentary side elevational view of the apparatusof FIG. 1 taken along the lines 2--2 thereof and illustrating one phaseof the operation of the sequentially staged linkage;

FIG. 3 is an enlarged fragmentary view of the particular linkage systemof the apparatus of FIG. 1 providing for gripping of the material to besealed;

FIG. 4 is an enlarged fragmentary view of the particular linkage systemof the apparatus of FIG. 1 providing for squeezing of the material to besealed;

FIG. 5 is an enlarged, fragmentary, side elevational view of the drivetrain linkage of the apparatus of FIG. 1 illustrating the first stage ofoperation and the placement of material to be sealed therein;

FIG. 6 is a view of a second stage of operation of the drive trainlinkage shown in FIG. 5; and

FIG. 7 is a view of a third stage of operation of the drive trainlinkage shown in FIG. 5 for further illustrating one embodiment of themethod and apparatus of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring first to FIG. 1, there is shown a perspective view of oneembodiment of the apparatus of the present invention. A heat sealingunit 10 includes a drive train or system 11 for engaging open endedtubular members 12 formed of conventional heat sealable material such asplastic and producing a sealed joint 14 as diagrammatically illustrated.The system 11 includes a first handle 16 connected to a drive shaft 18rotatably mounted through opposite side frame walls 19 and 21 of thesystem 11. The system 11 is supported and positioned by a pair of sideframes 22 affixed to and/or integral with said side frame walls 19 and21. Side frames 22 each upstand from a support base 20. An adjustableplatform 24 is slidably secured to said side frames 22 by fasteningmembers 25 engaging said side frames. A moveable product alignment rib26 extends across the platform 24 in generally parallel alignment withsaid shaft 18 for facilitating accurate positioning of tubular members12 to be sealed.

Still referring to FIG. 1 the system 11 includes first and secondgripping jaws 28 and 30 extending across the unit 10 in generallyparallel spaced relationship with the shaft 18. The gripping jaws 28 and30 are comprised of elongated gripping bars 31 and 32, respectively, andpairs of gripping bar connecting arms 33 and 34, respectively,supporting said gripping bars at opposite ends. The connecting arms 33are each pivotally mounted to the opposite side frame walls 19 and 21 insupport of gripping bar 31. Likewise, the connecting arms 34 are eachpivotally mounted to the opposite side frame walls 19 and 21 in supportof gripping bar 32. In this particular embodiment the connecting arms 33and 34 are pivotally mounted by gripping bar support shafts 38 and 40,respectively, which extend through side frame walls 19 and 21. Eachpaired set of gripping bar connecting arms 33 and 34 are responsive torotation of the shaft 18 through a first cam linkage comprisingeccentric members 44 and 45 secured to the shaft 18 adjacent saidgripping bar connecting arms. Eccentric member 44 is disposed outwardlyof side frame wall 19 between said gripping bar connecting arms 33 and34. Likewise, an eccentric member 45 (hidden from view in this figurebut shown in FIG. 3) is disposed between said gripping bar connectingarms 33 and 34 outwardly of side frame wall 21. A spring 47 is providedbetween each pair of gripping bar connecting arms 33 and 34 to bias saidarms one toward the other and toward the eccentric members 44 and 45.

Referring now to FIG. 3, the gripping jaw assembly above described isshown in isolation for purposes of clarity. It may be seen that eachgripping bar connecting arm 33 and 34 includes a laterally disposedshoulder portion 46 for abutting the eccentric member positionedadjacent thereto. Rotation of the shaft 18 in the direction of arrow 48thus causes the gripping bar connecting arms to move outwardly asindicated by the arrows 50, when the eccentrics 44 and 45 are in theposition shown in FIG. 3. It may also be seen that eccentric 44 isoppositely disposed upon shaft 18 relative to the "tear drop" shapedeccentricity region 52 of each eccentric for facilitating the necessarysequencing of the gripping operation of this particular embodiment. Byoppositely disposing said tear drop region 52, eccentric 44 will engagethe gripping bar connecting arm 33 adjacent side frame wall 19 causingboth arms 33 and the gripping 31 therebetween to rotate outwardly whileeccentric 45 provides the complemental arcuate motion to arms 34 andgripping bar 32.

Referring again to FIG. 1, there is shown the structure of first andsecond squeezing jaws 60 and 62 comprising another element of the system11 of the present invention. The squeezing jaws 60 and 62 extend acrossthe unit 10 in generally parallel spaced relationship with the shaft 18and are comprised of elongated squeeze bars 63 and 64, respectively, andpairs of squeeze bar connecting arms 66 and 67, respectively. Thesqueeze bar containing arms support said squeeze bars at opposite ends.The connecting arms 66 are each pivotally mounted to the opposite sideframe walls 19 and 21 in support of squeeze bar 63. Likewise theconnecting arms 67 are each pivotally mounted to the opposite side framewalls 19 and 21 in support of squeeze bar 64. Spring members 89 connecteach pair of connecting arms 66 and 67 and bias said squeeze bars 63 and64 one toward the other and about shaft 18. In this particularembodiment the connecting arms 66 and 67 are pivotally mounted by asingle squeeze bar support shaft 68 which extends through side framewalls 19 and 21. Each paired set of squeeze bar connecting arms 66 and67 are responsive to rotation of the shaft 18 for complemental actuationin system 11 as described below.

Referring now to FIG. 4, the squeeze bar assembly above described isshown in isolation for purposes of clarity. It may be seen that eachsqueeze bar connecting arm 66 and 67 includes an orthogonal Zconstruction having first and second linkage struts 70 and 72,respectively, in generally parallel relationship and joined by anorthogonal pivot leg 73 mounted to the shaft 68. Each paired set of arms66 and 67 are mounted in reverse, coaxial relationship, as shown,wherein the upper struts 70 are disposed about a series of eccentricmembers affixed to shaft 18 comprising a second cam linkage system. Asshown in FIG. 4, an eccentric 74 abuts strut 70 of an arm 67, eccentric76 abuts strut 70 of an arm 66, eccentric 78 abuts strut 70 of an arm ofan arm 66, and eccentric 80 abuts strut 70 of an arm 67. Rotation of theshaft 18 in the direction of arrow 82 thus causes the squeeze barconnecting arms to move outwardly as indicated by the arrows 84 asshown.

Referring once more to FIG. 1, there is shown a heat sealing element 90secured at opposite ends by heat element support arms 92 affixed theshaft 18 for rotation therewith. The heat element 90 is of conventionaldesign and may be heated electrically in a conventional manner (notshown for purposes of clarity) to a constant temperature. Since the heatelement 90 is positionally responsive directly to the rotationalposition of the shaft 18 a separate heat control is not necessaryrelative to its operation. The element 90 is simply rotated out of theway when not in use. This aspect of the present invention provides manyadvantages in that the heating stage of operation can only be effectedin conjunction with the proper sequencing of the squeezing and grippingoperations. For example, referring to FIG. 2, the heating element 90 isillustrated as retracting in direction of arrow 94 in response tomovement of handle 16 in the direction of arrow 96. The presence ofheating element 90 directly above a suitable tube 12 held by grippingjaws 28 and 30 causes end 93 of said tube to melt in preparation forengagement by squeezing jaws 60 and 62, shown moving to a squeezeposition by arrows 97 and 98. The opposite movements of jaws 60 and 62and element 94 via the single directional rotation of drive shaft 18 byhandle 16 is provided by the cammed linkage above discussed and is oneof the advantageous aspects of the operation of the present invention.

In operation, the unit 10 is supplied with conventional power such aselectricity for bringing the heating element 90 to the desiredtemperature. A water supply (not shown) is also preferably provided forcooling the gripping jaws 28 and 30 and squeezing jaws 60 and 62. Thewater supply lines (not shown) are generally connected directly to thegripping bars 31 and 32 and to the squeezing bars 63 and 64 for passagethrough the bars and the removal of residual heat collected fromengaging the heat sealed portions of the tubes 12. In this manner, themolten plastic of said tubes harden quicker with little surfaceadherence or sticking to said bars.

Referring now to FIGS. 5 through 7, and 2 in combination, four stages ofthe sealing sequence are shown for illustrating further both the methodand apparatus of the present invention. In FIG. 5, the tube 12 ispositioned upon platform 12 against rib 26, said platform and rib havingbeen adjunctably positioned for the particular size of said tube. Itshould be noted that in production operations a holding fixture (notshown) is usually incorporated to position a plurality of tubes 12 atone time. The jaws of FIG. 5 are of course, all open and the heatingelement 90 fully retracted as handle 16 lies in an open, ready positionfor initiating movement in the direction of arrow 100. It should benoted that handle and jaw positions are shown for purposes ofillustration only and may be selectively set in conjunction with thefirst and second cam linkages disclosed herein for varying therotational parameters, assembly stage, sequencing, and associated timeintervals for each operation segment. In addition, a second handle 17,shown in FIG. 1, is optionally provided for left hand operators. Sinceonly one hand is needed the operator has considerably more freedom touse the other hand to position material or perform associated functions.

Referring now to FIG. 6, the handle 16 has moved to an upper position ofarcuate displacement and the heating element 90 has been moved in thedirection of arrow 102. This rotational position of shaft 18 hasactuated the first and second cam linkages above described to close thegripping and sealing jaws as shown. In FIG. 7, the handle 16 has beenrotated to a position wherein the heating element is directly over thetube 12 for radiant heating of the plastic material thereof into amolten state. The squeezing jaws 60 and 62 are thus retracted. In FIG.2, the handle 16 is rotated in the opposite, return direction 96 causingthe squeezing jaws 60 and 62 to squeeze molten section 63 until both thesqueezing jaws and the gripping jaws open to release the sealed tube 14.As described, this method and apparatus substantially alleviates mostpotential operator error and maximizes time and efficiency in thesealing operation.

It is thus believed that the operation and construction of the presentinvention will be apparent from the foregoing description. While theapparatus as shown and described has been characterized as beingpreferred it will be obvious that various changes and modifications maybe made therein without departing from the spirit and scope of theinvention as defined in the following claims.

What is claimed:
 1. Apparatus for manually sealing heat sealablematerial in a manner requiring the use of only one of the two hands ofan operator by incorporating a single actuation drive train tosequentially grip, heat and squeeze heat sealable material positionedtherein, said apparatus comprising:at least one actuation handle formanual engagement by an operator and select arcuate motion; a driveshaft connected to said handle at one end and rotationally responsive toarcuate motion of said handle; a support frame supporting said driveshaft for rotational movement; a heat sealing element coupled to saiddrive shaft for movement in response to rotation of said drive shaft andthe heating of material disposed adjacent thereto; first and secondgripping jaws pivotally mounted to said support frame; first cam linkagesecured upon said drive shaft adjacent said gripping jaws for cammedactuation, separation and engagement of said gripping jaws in responseto rotation of said drive shaft; means biasing said gripping jawsagainst said first cam linkage; first and second squeezing jaws disposedbetween said gripping jaws and said heat sealing element and pivotallymounted to said support frame; second cam linkage secured upon saiddrive shaft adjacent said squeezing jaws for cammed actuation,separation and engagement of said squeezing jaws in response to rotationof said drive shaft; means biasing said squeezing jaws adjacent saidsecond cam linkage; means for supporting said material to be sealedbetween said support jaws and said gripping jaws; and said first andsecond cam linkages being connected to said drive shaft relative to saidheat sealing element for sequential actuation of said gripping jaws andsaid squeezing jaws relative to the rotation of said drive shaft by saidhandle and the positioning of said heating element relative to saidmaterial to be sealed.
 2. Apparatus as set forth in claim 1 wherein saidfirst and second squeezing jaws each includes at least one squeezeconnecting arm, a squeeze bar affixed said squeeze connecting arm, andmeans for pivotally mounting said squeeze connecting arm to said supportframe.
 3. Apparatus as set forth in claim 2 wherein said means forpivotally mounting said squeeze connecting arm includes a squeezesupport shaft mounted to said support frame and said squeeze connectingarm for rotational movement thereof.
 4. Apparatus as set forth in claim3 wherein said first squeeze connecting jaw includes a squeeze barpivotally connected to said support frame at opposite ends of saidsqueeze bar by first squeeze connecting arms and said second squeezeconnecting jaw includes a squeeze bar pivotally connected to saidsupport frame at opposite ends of said squeeze bar by second squeezeconnecting arms.
 5. Apparatus as set forth in claim 4 wherein said firstand second squeeze connecting arms each comprise an orthogonal Zconstruction having first and second linkage struts in generallyparallel spaced relationship and joined by an orthogonal pivot leg. 6.Apparatus as set forth in claim 5 wherein said first and second squeezeconnecting arms are mounted in reverse, coaxial positioning upon saidsqueeze support shaft, wherein said first linkage strut of each of saidsqueeze connecting arms is disposed adjacent said drive shaft and onopposite sides thereof and said second linkage strut dependstherebeneath in securement of said squeeze bar.
 7. Apparatus as setforth in claim 6 wherein said second cammed linkage comprises at leastone eccentric member secured upon said drive shaft in mating engagementwith said first linkage struts of said first and second squeezeconnecting arms.
 8. Apparatus as set forth in claim 6 wherein said meansbiasing said squeeze connecting arms comprises a spring member connectedbetween said second linkage struts of said first and second squeezeconnecting arms biasing said first linkage struts thereof toward firstand second eccentric members.
 9. Apparatus as set forth in claim 1wherein said first and second gripping jaws each comprise an elongatedgripping bar, gripping bar connecting arms affixed to said gripping barsat opposite ends thereof, and means for pivotally mounting said grippingbar connecting arms to said support frame.
 10. Apparatus as set forth inclaim 9 wherein said means for mounting said gripping bar connectingarms to said support frame includes at least one gripping bar supportshaft mounted in said support frame.
 11. Apparatus as set forth in claim10 wherein said first cammed linkage comprises at least one eccentricmember secured upon said drive shaft in mating engagement with saidgripping bar connecting arms for imparting pivotal motion to saidgripping bar connecting arms about said gripping bar support shaft inresponse to rotation of said drive shaft.
 12. Apparatus as set forth inclaim 11 wherein said second cammed linkage includes at least oneeccentric member secured upon said drive shaft with sufficienteccentricity to separate said first and second supporting jaws from saidmaterial to be sealed when said sealing element is positioned adjacentsaid material for the heating thereof and when said gripping jaws arethemselves separated one from the other for the positioning and removalof material therebetween.
 13. Apparatus as set forth in claim 1 whereinsaid drive shaft includes a second handle disposed at a second oppositeend of said shaft for permitting the operator to use either of the twohands.
 14. Apparatus as set forth in claim 1 wherein said heat sealingelement is affixed to said drive shaft for arcuate movement in responseto rotation of said drive shaft.